Bourdon tube pressure switch assembly



June 8, 1965 L. s. BARKSDALE 3,183,419

BOURDON TUBE PRESSURE SWITCH ASSEMBLY Filed Jan. 15, 1962 FIG. 1.

2 Sheets-Sheet l '26 V72 /.2 $23 20 f; 2a.

:9 k Rik-46 WARE/s, K7501, RussEL-L :& Y/(ERW June 8, 1965 L. s. BARKSDALE 3,183,419

BOURDON TUBE PRESSURE SWITCH ASSEMBLY Filed Jan. 15, .1962 2 Sheets-Sheet 2 F316. .3. .F'z'a. 4.

INVENTOE L /z BUR/V 5. 5A R/(SD ALE B Y HA5 A 770/?4/675' HARE/5, K/Ecw, E0551? (2 KERN United States Patent 3,188,419 BOURBON TUBE PRESSURE SWITCH ASSEMBLY Lilburn S. Barksdale, Los Angeles, Calif., assiguor to General Metals Corporation, San Francisco, Calif., a corporation of California Filed Jan. 15, 1962, Ser. No. 166,167 7 Claims. (Cl. 200-813) The present invention relates to pressure switches or pressure switch assemblies of the Bourdon tube type and general objects of the invention are to provide improvements in means for mounting such a pressure switch assembly in a housing in a fixed position, means for mounting a switch forming part of such an assembly, means for adjusting the pressure setting of a switch of such an assembly, and means for limiting the straightening deflection of a Bourdon tube of such an assembly.

In general, the invention contemplates a Bourdon tube pressure switch assembly which includes a housing, a pressure inlet fitting mounted'on and extending into the housing, a Bourdon tube mounted on and communicating with the pressure inlet fitting, a switch actuating element on the freeend of the Bourdon tube, one or more switches mounted in the housing and each having an actuator engageable by the switch actuating element, and adjusting means for adjusting the position of each switch actuator toward and away from the switch actuating element to vary the pressure setting for each switch.

An important object of the invention is to provide stop means, for positively limiting straightening deflection of the Bourdon tube under pressure, which is slidably adjustable relative tothe housing andwhich is engageable by theBourdon tube, coupled with means for locking the stop means in its adjusted position.

Another important object is to provide an adjusting means for varying the pressure setting for each switch which includes an adjusting screw extending through and having a head seated against a dome on a switch mounting bracket carrying the switch, this construction providingextrem'e accuracy even with imperfect alignment of the related parts. g v v I Still another object is to provide switch mounting brackets capable of fiexing for adjustment purposes to avoid any need for pivots, or like parts subjectto accuracy- 7 destroying wear.

A further important object is to provide a clamping means for clamping each switch mounting bracket onto a main mounting bracket in a simple, yetfreliable, manner and with the switch mounting bracket properly oriented relative to the main mounting bracket so as to properly position the actuator of the switch relative to the switch actuating element onvthe free end of the Bourdon tube. A related object is to provide a construction wherein the same main mounting bracket and clamping means may be used to support one or more switch mounting brackets, depending on whether one or more switches are required.

Yet another important object is to provide a main mounting bracket which is secured to the pressure inlet fitting and which is normally noncomplementary to and springable into seated engagement with a bracket engaging surface on the pressure inlet fitting, the invention providing screw means extending through the pressure inlet fitting and threaded into the main mounting bracket for springing the main mounting bracket into seated engagement with a bracket engaging surface of the pressure inlet fitting. With this construction, automatic locking means for preventing backing off of the screws mentioned are'provided.

Still another important object is to provide means for positively locking the pressure inlet fitting in a fixed position relative to thehousing to insure maintenance of the 3,188,419 Patented June 8, 1965 proper orientation of the Bourdon tube relative to the stop means.

The foregoing objects, advantages, features and results of thepresent invention, together with various other objects, advantages, features and results thereof which will be evident to those skilled in the art to which the invention relates, may be achieved with the exemplary embodiment of the invention described in detail hereinafter and illustrated in the accompanying drawings, in which:

FIG. 1 is an elevational view, with a housing cover removed, of a Bourdon tube pressure switch assembly of the invention;

FIGS. 2, 2a and 3 are sectional views respectively taken along the arrowed lines 22, 2a2a and 3-3 of FIG. 1;

FIG. 4 is an enlarged, fragmentary sectional view taken along the arrowed line 4-4 of FIG. 1;

FIG. 5 is a further enlarged, fragmentary sectional view taken along the arrowed line 5--5 of FIG. 1; and

FIG. 6 is a sectional view taken along the arrowed line 166 of FIG. 5.

. 12. Threaded on the fitting 20 externally of the housing is a nut 24. A lock washer 25 is inserted between the nut 24 and the exterior of the housing 12, the lock washer and a portion of the housing being clamped between the flange 23 and the nut 24.

The lock washer 25 is provided thereon with a lug ,25a

jammed or wedged between one of a pair of diametrally opposed flats 20a on the threaded portion of the fitting 20, and the corresponding one of a pair of diametrally opposed flats, or flat edge portions, 19a of the hole 19. With this construction, the fitting 20 is positively locked against rotation relative to the housing 12 to insure maintenance of the desired orientation of this fitting relative to a stop means 32 to be described hereinafter.

Threaded into the fitting 20 is a restrietor 28 for protecting the Bourdon tube 22 against pressure surges, the restrictor having a dampening effect thereon.

Secured to a head 29 on the free end of the Bourdon tube 22 is a switch actuating element in the form of a plate 30.

The stop means 32 includes a stop, 34 which is engageable at 34a, by the head 29 on the free end of the Bourdon tube 22, and, at 3412, by the convex side of the Bourdon tube adjacent the free end thereof, so as to limit straightening deflection of the Bourdon tube in response to increasing pressure therein, thereby preventing damage to the tube in the event of an excessive pressure. The stop 34 is adjustable relative to the housing 12 to permit accurate determination of the maximum straightening defiection permitted for the Bourdon tube 22. To achieve this, the stop 34 is provided at one end thereof with a slot 36 paralleling the adjacent wall 40 of the housing 12. At the other end thereof, the stop 34 is provided with an enlarged notch 38 facing the adjacent wall 40. Screws 42 and'44 extend through the slot 36 and the notch 38, respectively, and are threaded into bosses 46 and 48, respectively, on the wall 40 of the housing 12 to lock the stop 34 in its adjusted position. As will be apparent, the slot 36 permits vertical movement of the upper end of the stop 32, while the notch 38 permits both vertical and horizontal movement of thelower end thereof. Consequently, the portions 34a andfidb of the stop 34 can be positioned accurately to provide the desired limiting action.

The pressure inlet fitting 20 is provided, on the side thereof which faces the free end of the Bourdon tube 22,

with a flat bracket engaging surface 58, the latter being formed in part by fiat sides of laterally projecting lugs 60 on the fitting 2t Seated against the bracket engaging surface 58 of. the fitting 20 is a main bracket 62 having apertured dimples 54 into which are threaded screws 66 extending through the lugs 69. The main bracket 62 is formed of spring material and is initially bowed in such a manner that it has a concave side facing the. surface 58. When the screws 66 are threaded into the apertured dimples 64, they spring the main bracket 62 flat against the surface 58 so that the main bracket itself acts, in effect, to provide lock washers for preventing backing off of the screws. With this construction, a simple. and positive connection is provided with a minimum number of parts.

The main bracket'62 is providedat one end thereof, and within the are formed by the Bourdon tube 22; with a mounting flange 68 engageable by mounting flanges 7b of switch mounting brackets 72 each of which is generally channel shaped and receives therein a switch 74 secured by bolts 76. The switches 74 are preferably microswitches and are provided with actuators 78 in the formof buttons, engageable by the switch actuating element 30 at points" domes $2 are provided with slots 93 in directions perpendicularto the pivot axes provided by the hinges 88 to permit pivotal adjustment of the switches 74 without binding. The domes 92 permit accurate and permanent adjustments of the pressure settings of the two switches 74 despite minor misalignmeuts of the related parts in manufacture and assembly. 7

equidistant from the midplane of the Bourdon" tube 22.

While two switch mounting brackets 72 and two switches '74 are shown, it will be understood that this number may be increased or decreasedi The mounting flange 68 of the main bracket 62 is provided thereon with dimples 8t which fit into complementary holes 82 in the mounting flanges 70 of the switch mounting brackets 72 to key the mounting flanges 79 to the mounting flange 68. This construction automatically orients the switches 74 properly so as to properly position the actuators 78 thereof opposite the switch actuating element a The mounting flanges '70 of the switch mounting brackets 72 are clamped to the mounting flange 68 of the main bracket 62 by screws 83 extending through the mounting flanges 68 and 70 and threaded intoand through apertured dimples 84 in a nut plate 86 which is seated against the mounting flanges 70. Initially, the nut 'plate is transversely bowed to present a concave surface tothe mounting flanges 70. The screws 83 spring the nut plate 86 against the mounting flanges 70 so that the nut plate serves the function of lock washers for preventing backing off of the screws, thereby achieving a simple and positive clamping connection with a minimum number of parts. It' will be understood that this same clamping means may be used to mount only one switch mounting bracket 72 on the' main mounting bracket 62 if only one switch 7 4 is needed. a The mountingflanges 74 of the switch mounting brackets 72 are bent at angles to the main poritions of these 7 brackets to provide generally V-shaped portions 88 acting as flexible and resilient, wear-proof hinges which permit pivotal movement of the, switches 74 toward and away from the free end of the Bourdon tube 22 to permit varying the pressure settings of the switches.

The pressure settings of the switches 74 are respectively determined by adjusting screws 90 extending through and having heads seated against domes 92 on the switch tuators 78 relative to the switch actuating element 3th, v

and, thus the pressure settings of the respective switches 74, are determined by the adjusing screws 90. The

An important feature of the invention is that the Bourdon tube 22, the switches 74, and the adjusting means for the switches, are. all mounted on the fitting 20, which provides a simple and sturdy mount therefor.

Although an exemplary embodiment of the invention has been'disclosed herein for purposes. of illustration, it

wvill be understood that various changes, modifications (c) a Bourdon tube mounted on and communicating with said pressure inlet fitting;

(d) a switch' actuating element on'the free end of said Bourdon tube; l I (e) a rigid adjustable stop carried by and movable relative to said housing and directly engageable by said Bourdon tube to positively limit straightening deflection thereof; 7 v (flmcans for locking said stop in an adjusted position relative to said housing; and

(g) a switch mountedin said housing and having an actuator engageable by said switch actuating elernentr g ,2. In a Bourdon tube pressure switch assembly, the combination of: a r a (a) ahousing;

into saidhousing; I (c) a Bourdon tube mounted on and communicating with said pressure'inlet'fitting;

;(d) a switch actuating-elementon the free end of said Bourdon tube; j (e) a rigid adjustable stop carried by and movable relative to'said housing and directly engageable by said Bourdon tube to posistively limit straightening deflection thereof, said stop having enlarged screw holes therein; a

(f) screws extending through said screw holes and threaded into said housing for locking said stop in an adjusted position relative to said housing; and

(g) a switch mounted in said housing and having an actuator engageable'by said switch actuating element.

3. In a Bourdon tube pressure switch assembly, the

combination of:

(a) a housing;

(b) a pressure inlet fitting mounted on and extending into said housing; V 7 (c aBourdon tube mounted on and communicating with said pressure inlet fitting; V (d')' a switch actuating element on thefree end of said Bourdon tube; (e) a rigid adjustable stop carried by and movable relative to said housing and directly engageable by said Bourdon tube to positively limit straightening deflection thereof, said stop havingenlarged screw holes therein; 7 (f) one'of said screw holes being a slot oriented gen-. 'erally along a tangent to said Bourdon tube adjacent the free end thereof, and the other being a notch generally perpendicular to said slot; T (g) screws extending through said screw holes" and (b) a'pressure inlet fitting mounted on and extending threaded into said housing for locking said stop in an adjusted position relative to said housing; and

(h) a switch mounted in said housing and having an actuator engageable by said switch actuating element.

4. In a Bourdon tube pressure switch assembly, the

combination of:

(a) a housing;

(b) a pressure inlet fitting mounted on and extending into said housing;

(c) a Bourdon tube mounted on and communicating with said pressure pressure inlet fitting;

(d) a switch actuating element on the free end of said Bourdon tube;

(e) a switch in said housing and having an actuator engageable by said switch actuating element;

(-f) means mounting said switch in said housing for pivotal movement of said actuator toward and away from said switch actuating element, and in a position for engagement of said actuator by said switch actuating element, including a switch mounting bracket carrying said switch and having a dome thereon provided with a slot extending in a direc tion generally perpendicular to the axis of pivotal movement of said actuator; and

(g) adjusting means for adjusting the position of said actuator toward and away from said switch actuating element, including an adjusting screw extending through said slot and having a head seated on said dome.

5. In a Bourdon tube presure switch assembly, the

combination of:

(a) a housing;

(b) a pressure inlet fitting mounted on and extending into said housing;

(c) a Bourdon tube mounted on and communicating with said pressure inlet fitting;

(d) a switch actuating element on the free end of said Bourdon tube;

(e) said pressure inlet fitting having a bracket engaging surface;

(f) a bracket seated against said bracket engaging surface of said pressure inlet fitting, said bracket normally being noncomplementary to said bracket engaging sunface and being springab le into seated engagement with said bracket engaging surface;

(g) screws extending through said pressure inlet fitting and threaded into said bracket and springing said bracket into seated engagement with said bracket engaging surface;

(h) a switch in said housing and having an actuator engageable by said switch actuating element; and (i) means mounting said switch on said bracket in a position for engagement of said actuator by said switch actuating element.

6. In a Bourdon tube pressure switch assembly, the

combination of:

(a) a housing;

(b) a pressure inlet fitting mounted on and extending into said housing;

(c) a Bourdon tube mounted on and communicating with said pressure inlet fitting;

(d) a switch actuating element on the free end of said Bourdon tube;

(e) a main bracket mounted on said pressure inlet fitting;

(f) a switch mounting bracket having at one end thereof a mounting flange seated against said main bracket;

(g) interengageable keying means on said main bracket and said mounting flange for orienting said switch mounting bracket relative to said main bracket;

(h) a nut plate seated against said mounting flange on the side thereof opposite said main bracket, said nut plate normally being noncomplementary to said mounting flange and being springable into seated engagement therewith;

(i) a screw extending through said main bracket, said mounting flange and said nut plate and threadedly engaging said nut plate and springing said nut plate into seated engagement with said mounting flange to clamp said mounting flange between said nut plate and said main bracket with said switch mounting bracket properly oriented relative to said main bracket by said keying means; and

' (j) a switch mounted on said switch mounting bracket and having an actuator in a position for engagement by said switch actuating element.

7. In a Bourdon tube pressure switch assembly, the

combination of:

(a) a housing having a hole;

(b) a pressure inlet fitting mounted in and seated against said housing and having a threaded portion extending therefrom through said hole;

(c) a nut threaded on said threaded portion of said pressure inlet fitting externally of said housing;

((1) a washer on said threaded portion of said pressure inlet fitting bet-ween said housing and said nut;

(e) a lug on said washer jammed between a flat on said threaded portion of said pressure inlet fitting and a flat portion of the periphery of said hole;

(f) a Bourdon tube mounted on and communicating with said pressure inlet fitting;

(g) a switch actuating element on the free end of said Bourdon tube; and

(h) a switch in said housing and having an actuator engageable by said switch actuating element.

References Cited by the Examiner UNITED STATES PATENTS 1,075,419 10/ 13 Hickerson 151-25 1,849,481 3/32 DeLangie et al. 200-81 1,898,257 2/33 Nelson 73-411 2,300,895 11/42 Hopkins 200-81 2,415,034 1/47 Parker 200-81 2,703,259 3/55 Ncufield 285-161 2,831,091 4/58 Lang 200-81 BERNARD A. GILHEANY, Primary Examiner. 

1. IN A BOURDON TUBE PRESSURE SWITCH ASSEMBLY, THE COMBINATION OF: (A) A HOUSING; (B) A PRESSURE INLET FITTING MOUNTED ON AND EXTENDING INTO SAID HOUSING; (C) A BOURDON TUBE MOUNTED ON AND COMMUNICATING WITH SAID PRESSURE INLET FITTING; (D) A SWITCH ACTUATING ELEMENT ON THE FREE END OF SAID BOURDON TUBE; (E) A RIGID ADJUSTABLE STOP CARRIED BY AND MOVABLE RELATIVE TO SAID HOUSING AND DIRECTLY ENGAGEABLE BY SAID BOURDON TUBE TO POSITIVELY LIMIT STRAIGHTENING DEFLECTION THEREOF; (F) MEANS FOR LOCKING SAID STOP IN AN ADJUSTED POSITION RELATIVE TO SAID HOUSING; AND (G) A SWITCH MOUNTED IN SAID HOUSING AND HAVING AN ACTUATOR ENGAGEABLE BY SAID SWITCH ACTUATING ELEMENT. 